Newcastle Laboratories

International Normalised Ratio

Clinical Background:

This is the accepted method for controlling Vitamin K antagonist anticoagulant therapy (primarliy Warfarin). The patients Prothrombin Time (PT) is divided by the laboratory Mean Normal Prothrombin ...

This is the accepted method for controlling Vitamin K antagonist anticoagulant therapy (primarliy Warfarin). The patients Prothrombin Time (PT) is divided by the laboratory Mean Normal Prothrombin Time (MNPT) and the resulting ratio is then raised to the power of the ISI, to convert results to a common WHO standard.

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Test Details

  • Discipline:

    Haemostasis

    Haemostasis

  • Specimen Container Adult:

    Light blue - sodium citrate

    Light blue - sodium citrate

  • Specimen Container Paediatric:

    Light blue - sodium citrate

    Light blue - sodium citrate

  • Minimum Volume Adult:

    2.7mL

    2.7mL

  • Minimum Volume Paediatric:

    1.3mL

    1.3mL

  • Special Requirement:

    Tube must be correctly filled to line, to ensure correct ratio of blood to anticoagulant, ensure adequate mixing.

    Tube must be correctly filled to line, to ensure correct ratio of blood to anticoagulant, ensure adequate mixing.

  • Sample Stability:

    24 hrs

    24 hrs

  • Transport Requirements:

    Samples should be transported to lab without delay

    Samples should be transported to lab without delay

  • Freq Analysis:

    Continuous

    Continuous

  • Add On Test:

  • Quality Assurance:

    UK NEQAS Blood Coagulation

    UK NEQAS Blood Coagulation

  • Reference Ranges:

    1.5 - 4.0

    Dependent upon specific target value for patient.

    1.5 - 4.0

    Dependent upon specific target value for patient.

  • Other Info:

    To monitor warfarin like anticoagulants.

    To monitor warfarin like anticoagulants.

  • Routine Contact Name:

    RVI or Freeman Section Leaders

  • Routine Telephone:

    RVI: 0191 2820332, Freeman: 0191 2231195

    RVI: 0191 2820332, Freeman: 0191 2231195

  • Specialist Test:

    No

    No

  • Specialist Contact Name:

    Haematology and Haemostasis Healthcare Scientist

    Haematology and Haemostasis Healthcare Scientist

  • Specialist Telephone:

    0191 2139758

    0191 2139758

  • Specialist Email:

    alison.brown93@nhs.net

    alison.brown93@nhs.net

Availability:

All times, both sites

Turn Around:

Urgent within 1 hour.

Routine within 4 hours.

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